Testosterone and schizophrenia

Why are adolescent males at the highest risk for schizophrenia onset? And what is it about adolescence that makes male brains more vulnerable?

As any parent with a son knows, the teen years and male adolescence is a time of dramatic change in the body. What may not be so obvious is that dramatic changes are also taking place in the brain and mind and we are only just beginning to understand what these changes are.

In a recent study using laboratory rodents, I found that the increase in testosterone that males experience during adolescence contributes to key changes in the brain. It is now clear that hormones cross the blood brain barrier and many neurons in the brain express testosterone receptors enabling them to receive and respond to changes in these blood hormone levels.

Working out the role of hormones in the onset of schizophrenia continues.

My study is the first to show that adolescent testosterone increases synthesis of a brain chemical involved in motivation and reward, dopamine.

More interestingly, we found that testosterone increases levels of its receptor on dopamine neurons. This means that these important neurons become even more responsive to testosterone over time.

We speculate that the brains of people with an underlying susceptibility to schizophrenia are pushed over the edge into a hyperdopaminergic (increased dopamine) state and this may then result in psychosis. This is an important step towards understanding how testosterone may contribute to symptomatic dopamine-related psychopathology typical of schizophrenia.

This study highlights avenues to consider for sex hormone-related interventions at the first psychotic episode or even in individuals identified as at high risk for the disorder.

Dr Tertia Purves-Tyson is Senior Research Officer with the Shannon Weickert Group at NeuRA.

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